d7b3b802f4
shell parses arguments (very simplistic) readme version of README (sh doesn't deal with capital characters) printf recognizes %c nicer output format for ls
80 lines
1.4 KiB
C
80 lines
1.4 KiB
C
#include "types.h"
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#include "stat.h"
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#include "user.h"
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static void
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putc(int fd, char c)
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{
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write (fd, &c, 1);
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}
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static void
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printint(int fd, int xx, int base, int sgn)
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{
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char buf[16];
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char digits[] = "0123456789ABCDEF";
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int i = 0, neg = 0;
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uint x;
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if(sgn && xx < 0){
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neg = 1;
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x = 0 - xx;
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} else {
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x = xx;
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}
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do {
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buf[i++] = digits[x % base];
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} while((x /= base) != 0);
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if(neg)
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buf[i++] = '-';
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while(--i >= 0)
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putc(fd, buf[i]);
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}
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/*
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* printf to the stdout. only understands %d, %x, %p, %s.
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*/
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void
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printf(int fd, char *fmt, ...)
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{
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int i, state = 0, c;
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uint *ap = (uint *)(void*)&fmt + 1;
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for(i = 0; fmt[i]; i++){
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c = fmt[i] & 0xff;
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if(state == 0){
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if(c == '%'){
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state = '%';
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} else {
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putc(fd, c);
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}
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} else if(state == '%'){
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if(c == 'd'){
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printint(fd, *ap, 10, 1);
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ap++;
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} else if(c == 'x' || c == 'p'){
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printint(fd, *ap, 16, 0);
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ap++;
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} else if(c == 's'){
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char *s = (char*)*ap;
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ap++;
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while(*s != 0){
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putc(fd, *s);
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s++;
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}
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} else if(c == 'c'){
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putc(fd, *ap);
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ap++;
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} else if(c == '%'){
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putc(fd, c);
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} else {
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// Unknown % sequence. Print it to draw attention.
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putc(fd, '%');
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putc(fd, c);
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}
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state = 0;
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}
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}
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}
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